摘要
在吸收并修正部分前人工作的基础上,给出了电导率分块均匀的瞬变电磁2.5维有限单元法正演算法.在该算法中,(1)采用在矩形网格中进一步三角细化的剖分方式,同时考虑到矩形单元中心节点的性质,求解线性方程组前用高斯消元法消除矩形网格中心节点上的待求未知量,这样一方面较准确地模拟出任意二维复杂地电断面,另一方面又大大地节省了计算量;(2)采用计算二次场的算法,事先仅需获得电场和磁场沿地电构造走向方向两个分量的一次场,故而不但计算精度较高,而且不明显增加计算量.最后,对几例典型模型进行正演,并与解析解对比,验证了本文方法的有效性.
Based on absorption and modification of previous work, a numerical algorithm of the finite element method （FEM） for 2.5-D transient electromagnetic forward modeling with block homogeneous conductivity has been developed. Firstly, this method subdivides four triangnlar lattices by adding two diagonal lines in a rectangular cell, and then eliminates unknown variables to be calculated at the central node of the cell using the Gauss elimination before solving the system of linear equations. Thus, this method can be used not only to simulate accurately any complex 2-D geoelectrie section, but also to produce a considerable reduction of computation costs. At the same time, the algorithm presented in this paper for the secondary field only requires to compute two primary field components of electric and magnetic fields along the strike of geoelectrie structure beforehand, so it has relatively high computation precision and does not need much increase of calculation amount. Finally, some simple examples of electromagnetic fields produced by a central-loop source at sir-earth interface are presented to illustrate the usefulness of the method.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第2期590-597,共8页
Chinese Journal of Geophysics
基金
国家自然科学基金项目(40344022)
湖南省自然科学基金项目(05JJ30074)资助.
关键词
瞬变电磁
2.5维正演
有限单元法
电导率分块均匀
Transient electromagnetic, 2.5-D forward modeling, FEM, Homogeneous. conductivity within each block
